Pain is a highly prevalent experience with a significant impact on physical and psychosocial functioning and an economic burden amounting to billions of dollars within the U.S. alone. Many scientific and healthcare organizations are now calling for improved assessment as a means to better treatment of pain. Language offers one valuable medium for the assessment of pain and it has encouraged the development of psychometric tests based on pain descriptors. The broad objective of the proposed research is to build on a foundation of pain assessment that started with the McGill Pain Questionnaire (MPQ). At its inception over 30 years ago, the MPQ was viewed not as a final product but as one amenable to revision. Recent factor analytic findings underscore this need for improvements in verbal descriptor assessment of pain. The aim of the proposed research is to psychometrically evaluate a new instrument called the Pain Descriptor System (PDS). Items of this instrument are based on three separate publications (by the author and colleagues) that point to a parsimonious set of 36 pain descriptors that are highly comprehensible, relevant, and unambiguous. The proposed research is designed to (i) to establish the construct validity of the PDS through confirmatory factor analysis and item response theory, (ii) to determine the internal consistency of the PDS as indexed by Cronbach's alpha, (iii) to determine the one week and one month retest reliability of PDS scores as measured by temporal stability correlations, (iv) to check the predictive validity of the PDS in relation to (physical and psychosocial) disability as measured by an instrument called the PDQ, and finally (v) to ascertain the diagnostic value of the PDS by relating patterns of descriptor choice to different painful conditions (three types of headache and three chronic pain syndromes); this will be done using discriminant analysis. A team comprising a pain scholar, a psychometric statistician, and 3 pain clinicians will collaborate in this two-year project which involves 660 patients as participants. The expected outcomes are improved quantification and qualitative characterization of pain, and thereby improved diagnosis and prognosis of pain and disability. The findings from this program of research are expected to improve the quantification and qualitative characterization of pain through use of the new and convenient test called the Pain Descriptor System. This instrument is also expected to enhance the prognosis of pain-related disability and the differential diagnosis of pain syndromes. Ultimately, the improved assessment and diagnosis of pain can inform and guide the treatment selection and treatment planning for pain patients. [unreadable] [unreadable] [unreadable]